Front panel overlays, sometimes referred to as flat panel displays, are widely used in a variety of applications such as, but not limited to, household appliances, medical equipment or devices, personal electronics, calculators, computer keyboards, machinery panels, control panels, and the like. Generally speaking, one function served by a front panel overlay is as an operator interface for the device to which it is mounted. Depending on the device, the front panel overlay may include a number of input/output mechanisms such as lights, push buttons, switches, displays, gauges, and meters allowing a user to do such functions as turn the device on or off, enter operating instructions, time device operation, monitor parameters of the operation, and the like.
To allow for the front panel to receive such information, the front panel overlay often includes a membrane switch behind, or otherwise associated with the input/output mechanisms, which receives that input. The front panel display then transmits associated signals back to a motherboard recessed deeper within the device, receives processed signals back from the motherboard, and then displays those signals to the user by way of the output mechanisms on the front panel overlay.
The front panel display typically includes several layers, such as a graphics layer for interfacing with and receiving commands from the user by way of the aforementioned input/output devices, one or more circuit layers forming the membrane switch and containing the electronic circuitry, and optionally a base layer for providing stability and support to the otherwise flexible layers of the front panel display. Such membrane switches have several advantages over other forms of switches (e.g., mechanical switches) that are commonly employed. For example, membrane switches present a substantially flat upper surface and, they are thin and flexible, which allows them to be used in locations that may be difficult for mechanical switches to reach. Also, membrane switches are enclosed, and contain very few moving parts, so they are reliable, not impacted by dust, moisture or liquids and have long useful lives in a variety of environments. When used on medical devices and equipment, these attributes allow for a more sterile unit that can be easily cleaned and maintained.
While effective, such prior art approaches have, as mentioned above, required that the signals received at the front panel overlay be entered through the membrane switch, and then be communicated by way of associated signals back to a remote processing unit, such as a motherboard or printed circuit board, situated deep within the device on which the front panel overlay is mounted. This necessarily requires that the front panel overlay be connected to the remote electronic processing unit using a plurality of conductive traces and interconnects via a flexible cable or “tail” running from the front panel overlay to the remote electronic processing unit. The connections between the front panel overlay and the remote electronic processing unit are not only complex, they drive the cost of the device up and unnecessarily consume space within the device that may otherwise be used for enhancing the functionality of the device.
It would accordingly be beneficial if an improved front panel overlay having at least some local processing capability could be developed. It would additionally be beneficial if such an improved front panel overlay could at least partially reduce the number of connections between the front panel overlay and the remote electronic processing unit of the device employing the front panel overlay.